fix(csp): hash the exact emitted inline style bytes

[seonghobae]

Problem

The generated page declared a style-src SHA-256 hash for an inline stylesheet, but template indentation and leading/trailing whitespace could make the emitted <style> text differ from the string that was hashed. Browsers then block the stylesheet under the otherwise restrictive CSP.

Repair

• normalize the immutable stylesheet once with trimIndent();
• calculate its SHA-256 Base64 source expression once per process;
• inject exactly that normalized string between the <style> tags;
• retain default-src 'none', base-uri 'none', and form-action 'none' without adding unsafe-inline or a broader source;
• remove the duplicated per-directory digest work;
• document the current CSP Level 3 byte-matching contract and threat boundary in docs/doctoring with an APA 7th reference; and
• record the change under Unreleased in CHANGELOG.md.

Product-level regression

CspHashTest.emittedStyleBytesMatchTheDeclaredCspHash creates a real temporary directory, invokes process_dir, extracts the actual emitted style text and CSP hash-source, independently recomputes SHA-256 over the exact UTF-8 bytes, and requires equality. It also rejects leading or trailing template padding.

Verification

The regression-test commit passed repository CI, JaCoCo coverage verification, Security Scan, and Semgrep. The current exact head must pass fresh versions of those checks plus current-head automated and independent review before merge. Queued, skipped, cancelled, absent, stale-head, or failed results are not treated as success.

No formal W3C conformance claim is made; the cited CSP Level 3 publication is a current Working Draft.

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📥 Commits

Reviewing files that changed from the base of the PR and between a3c445e and 832e39e.

📒 Files selected for processing (5)

• .jules/sentinel.md
• CHANGELOG.md
• docs/doctoring/csp-inline-style-byte-identity.md
• src/main/kotlin/html4tree/main.kt
• src/test/kotlin/html4tree/CspHashTest.kt

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